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Finding the Fourth Proportional to 1,378.80, 1,902.02 and 819

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Solution

The fourth proportional to 1,378.80, 1,902.02 and 819 is: 1,129.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,378.80 : 1,902.02 = 819 : x
  2. Step 2: Convert to fraction form
    1,378.80/1,902.02 = 819/x
  3. Step 3: Cross multiply
    1,378.80x = 1,902.02 × 819
  4. Step 4: Simplify right side
    1,378.80x = 1,557,750.29
  5. Step 5: Solve for x
    x = 1,557,750.29/1,378.80
  6. Step 6: Final answer
    x = 1,129.79

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.